The present invention relates generally to a new and improved construction for a cutting tool holder. More particularly, the present invention relates to a quick connect/disconnect mechanism for a cutting tool head for cutting a rotating workpiece
Conventional cutting tool holders consist of a shank which is attached to the cutting tool to which is attached a cutting head. The cutting tool, in operation, causes the shank and cutting head combination to move to and fro with respect to a rotating workpiece Typically, the shank is adapted to receive a wide variety of cutter heads.
With such conventional cutting tools, however, the cutting heads are typically secured to the shank by means of a bolt which passes through the cutting head and into the shank. Thus, in order to change cutting heads, it is necessary to remove the bolt, which requires a relatively great amount of time. That is especially true in light of the fact that cutting heads must be changed often thousands of times per year for each cutting machine. In addition, such operation requires the use of both hands of the operator and must be performed with care in order to prevent the accidental breakage by dropping of the cutting head.
Since cutting tool machines have been developed which no longer require an operator during operation, there is a great need for a simple and quick, yet effective, mechanism for connecting and disconnecting a cutting head from a cutting tool shank in order to return the cutting machine to operation as soon as possible.
One type of cutting tool has been suggested in which a cutter can readily be attached to and detached from the arbor head without removing the bolt typically used to secure those parts together. In U.S. Pat. No. 4,325,664, to Mori, there is shown such a system. However, in addition to the bolt, which utilizes two enlarged portions over which the cutter is fitted, two pins and two machined recesses are necessary in order to properly align the cutter to the cutting tool and to keep the cutter from rotating relative to the cutting tool. Another disadvantage is that additional time is wasted in having to secure the cutter in that manner.
In another type of cutting tool, such as that disclosed in Cellini, U.S. Pat. No. 3,730,637, the tool holder has a shank with threads on one end and the head has a threaded aperture. The threads on the head are adapted such that they mate with the threads of the shank. The threaded end of the shank is inserted into the aperture in the head and rotated in order to tighten it. Since this cutting tool holder construction utilizes threads as the means to attach the head to the shank, rotation of the head with respect to the shank may occur during operation over an extended period of time.
In still another type of cutting tool, such as that disclosed in U.S. Pat. No. 4,270,422 to Anderson, the shank is provided with a lockpin which extends from within a bore in the shank into a bore in the head. The lockpin is provided with an enlarged portion on one end which engages with a recess in the head which is shaped and sized to receive the enlarged portion. The head is held in contact with the shank by means of a spring force which acts on the enlarged portion and serves to lock that enlarged portion within the recess In such a design, movement between the head and the shank may develop over time due to wearing or warping of the enlarged portion and the recess.
Yet another approach, such as that disclosed in Haga, et al., U.S. Pat. No. 4,274,774, discloses a tool which is held to a shank by means of a bayonet end which is insertable into an aperture and rotatable to engage the aperture walls. The bayonet end has protrusions that are L-shaped such that when they are inserted part way they can only be partially rotated and, at that extent, they engage the aperture walls. The bayonet is spring loaded so that it acts as an anti-rotation device. Although, the Haga, et al. system provides some protection against rotation of the tool relative to the shank, with use over time, such design may result in the warping of the protrusions and the aperture so as to allow a certain amount of play to develop between the tool and the shank.